Breathing Problems if sleep after eating

In 2020 March, I developed some breathing problems. After consulting doctor, they told it might be GERD and gave Cintodac medicine, and told not to sleep after having food. I took Sucral O before food and slowly it disappeared. Also did an endoscopy and they found nothing. The problem now is, if I even lay down for few mins after having even some snacks, I start getting problems in breathing the next day. Upper abdomen starts paining a little and stool becomes sticky, sometimes I don't have any bowel movement for 1-2 day when this problem happens. Again when breathing problem resolves, stool and bowel movement also becomes normal. I am not sure what is happening. I am taking proper fibrous food and drinking water, walking daily even then if I lay down after having any food, I get this issue. What to do?